1. Field of the Invention
The present invention relates to a method of manufacturing a wiring substrate having a built-in component (hereinafter referred to as a “component-built-in wiring substrate”) in which a component, such as a capacitor, is incorporated.
2. Description of Related Art
In association with a recent increasing tendency toward higher operation speed and higher functionality of semiconductor integrated circuit devices (IC chips) used as, for example, microprocessors of computers, the number of terminals have increased and the pitch between the terminals has tended to become narrower. Generally, a large number of terminals are densely arrayed on the bottom surface of an IC chip and are flip-chip-bonded to terminals provided on a motherboard. However, since the terminals of the IC chip differ greatly in pitch from those of the motherboard, difficulty is encountered in bonding the IC chip directly onto the motherboard. Thus, according to an ordinarily employed method, there is fabricated a semiconductor package configured such that the IC chip is mounted on an IC chip mounting wiring substrate, and the semiconductor package is mounted on the motherboard. In the IC chip mounting wiring substrate which partially constitutes such a semiconductor package, in order to reduce switching noise of the IC chip and to stabilize supply voltage, provision of a capacitor is proposed. For example, a wiring substrate having the following configuration is conventionally proposed: a capacitor is embedded in a core substrate made of a polymeric material, and a build-up layer is formed on each of opposite sides of the core substrate (refer to, for example, Patent Documents 1 and 2).
An exemplary method of manufacturing the above-mentioned conventional wiring substrate is described below. First, there is prepared a core substrate 204 made of a polymeric resin and having an accommodation hole 203 which opens at both of a core main-surface 201 and a core back-surface 202 (see FIG. 15). Also prepared is a capacitor 208 having a plurality of surface electrodes 207 which are provided in a projecting condition on a capacitor main-surface 205 and a capacitor back-surface 206 (see FIG. 15). Next, a taping step is performed for affixing an adhesive tape 209 to the core back-surface 202, thereby sealing the opening of the accommodation hole 203 on a side toward the core back-surface side 202. Then, an accommodation step is performed for accommodating the capacitor 208 in the accommodation hole 203 such that the capacitor back-surface 206 is affixed to the adhesive surface of the adhesive tape 209 for temporary fixation (see FIG. 15). Next, a gap A1 between an inner wall surface 210 of the accommodation hole 203 and the side surfaces of the capacitor 208 is filled with a portion of a resin filler 211 in contact with the core main-surface 201; then, the resin filler 211 is cured and shrunk, thereby fixing the capacitor 208 in place (see FIG. 16). Then, after the adhesive tape 209 is removed, resin interlayer-insulation layers and conductor layers are alternatingly laminated on the core main-surface 201, thereby forming a main-surface-side build-up layer; similarly, resin interlayer-insulation layers and conductor layers are alternatingly laminated on the core back-surface 202, thereby forming a back-surface-side build-up layer. As a result, a desired wiring substrate is yielded.